Transport Independence
Certificates can be requested and distributed through any transport mechanism. Certificate Services accepts certificate requests from an applicant through HTTP, DCOM, RPC, disk file, or by custom transport. Certificate Services posts certificates to the applicant through HTTP, DCOM, RPC, disk file, or custom transport.
Transports are supported by intermediary applications and exit module DLLs, usually written in C/C++. The intermediary applications and exit modules isolate Certificate Services functions from communicating with any specific transport.